The attentive cerebellum - myth or reality?

Based on the discovery of significant cerebellar projections into associative cortices and the observation of cerebellar abnormalities in autistic children, the concept has been put forward that the cerebellum might contribute to cognitive functions including attention. Specifically, a deficit analogous to motor dysmetria has been envisaged as a consequence of cerebellar damage - the `dysmetria of attention'. This paper provides a review of patient studies and imaging studies which have been performed so far in order to test this concept. Although several sudies report on attention deficits of patients with cerebellar damage, a closer look at the specific paradigms used reveals that disturbances have only been observed consistently for tasks involving significant oculomotor, motor, and/or working memory demands. Likewise, cerebellar activations in imaging studies on attention seem to reflect oculomotor or other motor behavior rather than true involvement in attention. Both attempts have failed so far to consistently reveal cerebellar involvement in attention when confounding influences were controlled. We, therefore, conclude that the concept of attentional dysmetria as a consequence of cerebellar damage is not adequately supported.